An amateur astronomy song

In honor of the festive season and all those new telescopes gifted, here's my gift to you: maybe not the world's first amateur astronomy song (that goes perhaps to Twinkle Twinkle Little Star), but a rarity nonetheless. I wrote the lyrics from hardened experience and set them to music with Suno AI.

Happy Holidays!

Listen to "The Forecast":

(Reindeer by Nigel Hoult, CC by 2.0, edit by Astronomerica)

Learning to use your first telescope

The internet is bursting at the seams with telescope reviews, which is why I try not to add to that. However, it is harder to find some comprehensive advice regarding what to do when you get that package in the mail, put it together, wait two weeks for the sky to clear (the "curse" of buying a new telescope), and are ready to start observing.

Learning the telescope

Of course you will be eager to start observing, but before you put your new telescope outside under the stars, make sure you read the instructions, whether included with the telescope or found online. Put it together properly and understand what each part does. If you don't, you might end up frustrated that you can't find anything or wondering why everything just looks like a blob.

DO NOT start tweaking collimation, if your telescope allows it, until you know what you are doing. I can't count how many times beginners go online saying they can't see things well in their telescope and because they've heard about collimation they immediately think that's the problem and hopelessly screw up the telescope's alignment. Most telescopes are reasonably well collimated out of the factory and won't be out of alignment so bad that it will even be noticeable to a beginner. They also tend to hold collimation extremely well, so while it's something you will need to learn to do eventually, it's not something I recommend a beginner start messing with. That's a rabbit hole you don't need to go down when you are starting out.

Tripod and/or mount

Steady views are good. Most inexpensive telescopes that beginners buy, except for Dobsonians, tend to be undermounted, giving shaky and frustrating views. That's why advanced amateurs, especially imagers, spend gobs of money on big heavy mounts and tripods. The tripod is the three legged stand that holds the mount, which holds the telescope optical tube assembly (OTA). The mount provides movement in two axes, either in altitude and azimuth or right ascension and declination. Either system allows you to point the telescope tube anywhere in the sky.

Hopefully your telescope's mount is reasonably sturdy. If not, it's not the end of the world. You simply wait a few seconds after touching it (moving the tube to an object, focusing, etc.) for the vibrations to die down. If it's windy and you have a shaky mount, try to get behind a car or the side of a building to minimize the effect. Or just wait until it's not so windy. 

Left: The Explore Scientific FirstLight 102mm refractor, with main parts labeled.

A far greater impediment to observing is if the mount is difficult to move smoothly. This is where Dobsonians shine. You simply push the tube where you want it to go. I recommend putting one hand up on the lip of the aperture and the other near the back of the tube. This gives you more precise control and leverage.

Right: A Dobsonian reflector, such as the Apertura AD8, is a simple design that maximizes aperture and stability per dollar spent.

For tripod-mounted scopes, a lower quality mount will really become an issue when you try to move the scope to center an object and track it manually. Some just aren't designed well or are cheaply manufactured, making these operations incredibly frustrating. This is why I like slow motion controls. These are semi-flexible cables with a knob on the end that you turn to allow you to move the scope in finer increments than by just pushing the tube around. 

Main optics

Telescopes work by collecting as much light as possible using a larger aperture than the pupil of your eye. Refractors do this using a set of lenses. Reflectors use a large parabolic-shaped mirror. Catadioptrics (Schmidt-Cassegrains, Maksutov-Cassegrains, for example) use a combination of lenses and mirrors to create a light path that folds back upon itself. The larger the aperture, the more light the telescope collects. 

By concentrating and focusing this larger amount of collected light into a spot roughly the size of your pupil, a telescope allows you to see dimmer objects and more detail in even bright objects like the Moon or Jupiter. You look through an eyepiece inserted into the telescope where the light comes to focus. The eyepiece contains multiple lenses to magnify the image. In short, the telescope collects and concentrates the light, the eyepiece magnifies it.

Redirecting the light path for comfortable viewing

If you have a refractor or catadioptric ("cat") telescope (like a Schmidt-Cassegrain or a Maksutov-Cassegrain), you will first insert a diagonal, usually containing a mirror tilted at 90 degrees, and insert the eyepiece into that. The diagonal ensures that you have a comfortable position for viewing high up in the sky. If your scope comes with a 90 and and 45 degree diagonal, use the 90 for astronomy and the 45 for terrestrial viewing.

Because the diagonal is usually held in by a couple of thumb screws, you can rotate it to position it more comfortably for viewing. This will change the orientation of the view in the eyepiece, like tilting your head, but you learn to know which way is which after a while. There's no law saying you have to have it set vertically and look straight down into the eyepiece.

A reflector has a diagonal of sorts, too, but it's built into the upper part of the telescope tube. It's called the secondary mirror, and like the mirror diagonal, it's a flat mirror that redirects the focused light path 90 degrees so you can view in a comfortable position, either on the left or right side of the front of the tube.

Generally, a refractor or catadioptric will mirror-reverse the view. A Newtonian reflector will simply rotate it 180 degrees. Understanding directions in your eyepiece will help you make sense out of what you are seeing compared to a chart or image.

Changing magnification

Eyepieces, what some people call "lenses" (or "oculars" for the more esoteric term), are how you change magnification, or power. Except for specific eyepieces with a rotating barrel that actually are zoom lenses, each eyepiece will give you a fixed power depending on its focal length and that of the telescope. You change magnification by changing eyepieces. 

The standard eyepiece barrel diameter is 1.25". However, many telescopes have 2" focusers, allowing for larger eyepieces with 2" barrel diameters. Most of these come with a 1.25" adapter so you can use both, or you can buy one.

Magnification (or power) = telescope focal length / eyepiece focal length. So a 750mm focal length telescope with a commonly included 25mm eyepiece will give you 30 power (30x)—magnifying 30 times what your unaided eye sees. Place the eyepiece in the focuser or diagonal, making sure it's seated all the way in, and use the thumbscrews to clamp it tightly so it won't fall out. It doesn't matter how it's rotated. 

It's best to remove an eyepiece before you move the telescope to prevent it from falling out if the thumbscrews aren't tight. Get in the habit of frequently checking the tightness of all thumbscrews for eyepieces, diagonals, and finderscopes. After 30+ years with no incident, I recently had an 8x50 finderscope fall from the upright tube of my 10-inch Dobsonian onto the cement floor of the garage. Surprisingly, no damage, but it does happen. (Most finderscopes have a tab on one side of the base of the bracket, however the ones I've seen are always toward the back, where they don't help to prevent the finderscope from sliding out on a reflector, as mine did. Makes more sense to me to have the tab in the front, but it's a refractor thing.)

Taking a seat

Although I stood the first dozen or so years when observing with a telescope, I highly recommend finding a good seat and sitting while you observe. You will be more comfortable, you will get a steadier view, and you won't tire so quickly.

The longer the tube of your telescope, the more variation there will be in the height of the eyepiece as you view objects around the sky. You can get by with a stool or chair for a shorter tube, and for telescopes that use a diagonal you can rotate it to make up some of the difference, but longer tubes such as larger Dobsonians will require an adjustable chair. 

You can decide later if you want to spend the money on a commercially available observing chair, such as the Starbound, Vestil, Catsperch, or build your own. Some people also buy and use drum thrones with varying degrees of success. 

I built my own Denver Observing Chair, a popular option, for my 10-inch Dobsonian but I often use a collapsible stool for my 6-inch tabletop Dobsonian and 102mm Maksutov-Cassegrain.

Right: My homemade Denver Observing Chair that has served me well for over 20 years.

Finding objects

Your telescope should have some sort of finderscope, either what amounts to a tiny refractor mounted on the main scope that magnifies the view or a red dot or red circle finder that projects a dot or circle on a tilted glass or plastic surface and makes it look like the dot is projected onto the sky with no magnification. In either case, it is absolutely critical that you align the finder with the telescope. The finder has a low power (in the case of a red dot, 1x) and wide field so it's easier to find objects than looking directly in the main telescope.

Before searching for anything, focus your finderscope if you have one. This is usually done by loosening a ring near the objective lens and screwing the lens housing in or out, then retightening the ring. Also put your lowest power/widest field eyepiece in the telescope's main focuser and focus on any random stars. Focusing tips are covered later in this article.

Above: Simulated view of the field for the Owl Nebula, M97, in an 8x50 straight-through finderscope on a Dobsonian telescope in a light polluted sky. The view will be rotated 180 degrees from the naked eye view, which matches the view in the eyepiece.

Left: Screenshot from Sky Safari Pro showing the 8x50 field of view, rotated to roughly match the finderscope view above. You can customize the field of view to match your own equipment, which helps to match what the chart is showing to what you are seeing in the finderscope and eyepiece. The small circle around the planetary nebula symbol is the eyepiece filed of view. You can see how much more difficult it is to find something in the eyepiece without first centering it in the finderscope.

Sometimes the labels and other clutter can obscure some of the stars, so be careful. Zoom the screen in and out to see what might be hidden.

Below: Simulated view of the same field for the Owl Nebula, M97, in a red dot finder, also in a light polluted sky. The brightest star in both views is Merak, or Beta Ursae Majoris, magnitude 2.3. The view is the same as your naked eye view, with fewer stars visible than in a magnifying finderscope. 

In neither finder will M97 be visible, so you need to aim based on the location in relation to the star patterns from a star chart and what you can see in the sky. Without the magnification of a finderscope, the red dot loses a lot of precision, so it's critical that you use the lowest power/widest field eyepiece that you have once you are pointed in the right general direction. 

Sometimes, especially if the object is very dim and you may not recognize it right away, it's better to start by pointing the red dot at the nearest bright star, Merak in this case, then switching to the eyepiece and starhopping your way to the object by comparing the star patterns in your eyepiece to those on the chart. This sounds simple, but it's often difficult to be sure exactly where you are pointing, and it's easy to get lost along the way. It still happens to me all the time. It takes practice and, even with experience, patience.

It's easiest to do the finder rough alignment in the daytime. Find a distant fixed object, like the top of a telephone pole. Put your lowest power eyepiece in (the one with the highest mm number) and center the object in the telescope. Then, without moving where the scope is pointing, look in the finder and use the little thumbscrews on the side of it to put the same object in the center or crosshairs. Do this a couple of times, even using a higher power eyepiece for more accuracy, until you are sure they match.

Each time you go out observing, check the finder alignment on a bright object like the Moon, Jupiter, or a bright star, something you'll be certain you are pointed at. First in the main telescope, then in the finder and adjust the finder as needed.  Then when you use the finder to locate an object, it will show up in the main telescope eyepiece. Depending on how accurate the alignment is and how well you positioned the object in the finder, you may need to look around in the main telescope eyepiece a little to find it. Use low power when searching. You can always switch to higher power later.

Some telescopes have a go-to computerized mount, which requires battery power and must be leveled and aligned prior to observing. These aren't as foolproof and simple as they sound, and they often don't work right. They will have tracking, though, which keeps an object more or less centered in the eyepiece. These usually come with a hand controller or are controlled via an app. 

Another computerized navigation system is a variation of a push-to configuration, where an app guides you with arrows to manually push the telescope to the location of an object. Again, this must be aligned or calibrated. The Celestron StarSense app is a good example. It takes pictures of the sky and matches them to an internal database. A freeware push-to app is AstroHopper, which requires frequent recalibration but otherwise is a good alternative to pure starhopping or expensive commercial push-to systems.

Focusing

The basic rule for focusing is to slowly turn the focusing knob, or the focuser itself in the case of the helical focuser found on many tabletop telescopes, until the object gets as small and sharp as it can be. If it does so, but then gets larger and fuzzier as you keep turning the knob, then you know where the point of focus was and that you have passed it. Just go back slowly and find it. You may have to tweak the focus in very small increments back and forth until you get the best focus possible for the seeing conditions. Usually you will have to let the scope vibrations settle after each tweak. This is normal unless you have an exceptionally sturdy mount. If your telescope has a dual-speed focuser, you can use the smaller knob for fine focus adjustment, much the same for focusing as slow motion controls on a mount are for centering and tracking objects with more precision.

Stars should look like points in low power. However, in high power, you may begin to see the "Airy disk," which is the tiny disk of light that the star is spread out into due to the optics in your telescope, its size dependent upon the aperture of your telescope. Dimmer stars will still look like points in high power, but the brighter ones should look like tiny disks surrounded by a thin circle or two, called diffraction rings. This is what you want in a well focused and collimated telescope.

Above: If you look closely, the Airy disks and diffraction rings of the two brightest stars are visible in this simulated high power telescope view. Too often Airy disk images are blown way up in scale so you don't know what you should be seeing.

What if things don't look sharp?

Assuming thin clouds aren't obstructing your view and your focus is the best it can be, then by far and away the likeliest culprit is atmospheric turbulence, or what astronomers call "poor seeing." This is what causes bright stars to "twinkle." The seeing changes based on your location, night to night, and even minute to minute. Some places in the world frequently have very good to excellent seeing, or steadiness. Examples in the United States include much of the western U.S., as well as Florida. The northern, eastern, and midwestern U.S. are often under the jet stream, meaning nights of very good or excellent seeing are rare. 

Below: Jupiter and its Galilean moons in good seeing (L) and bad seeing (R). (Jupiter images by TheWitscher via Flickr, CC By 2.0, modified to simulate seeing conditions in eyepiece.)

You'll get used to knowing what's good and bad seeing through experience. When Jupiter, Saturn, or the Moon look like they are sitting in the bottom of a clear flowing stream, you have very poor seeing. Stars will look like undulating blobs. The view will shimmer and boil as waves of thermals pass in the atmosphere. You may not be able to make out a bright star's sharp Airy disk or diffraction ring in high power. Every object will just be a moving mess. 

Don't give up just because the seeing isn't great. It's not uncommon to have very brief moments when the air steadies out despite bad seeing. It might only be a split second every few seconds, but you can see a lot in those short bursts of good seeing.

Extended objects like galaxies and nebulae are less obviously affected by seeing, so if you have a very clear night but poor seeing (a common combination), go for those types of objects. 

At the other extreme, excellent seeing means you see stars as steady points or Airy disks, bright planets seem to be much larger than you remember and show a lot more detail to an experienced eye. You can see tiny craterlets on the Moon, the shadows are sharply defined with no double-edges, and you see little or no shimmering.

Seeing is also affected by thermal currents within the tubes of some telescopes, mainly reflectors and catadioptrics. Refractors not so much, if at all. This is why you will see some Dobsonian owners with fans installed to blow air through the tube, or "cat" owners who wrap their tubes in Reflectix or other insulating material. It's all to make sure the scope design is not contributing to poor seeing. In the former case, they are trying to cool the mirror down to ambient temperature or remove thermal layers inside the tube. In the latter, they are trying to slow down and distribute the cooling so there are no big temperature differentials or plumes inside the tube to cause poor seeing. 

In most cases. setting a reflector or "cat" outside for an hour or so before observing will help, but it's not always possible, given your situation. Just be aware that it may take time for the scope to "settle."

What about collimation?

Rarely is it the case where collimation, the alignment of the telescope's main optics, is so bad that it spoils the view as much as bad seeing. There are tools you can use to check and adjust collimation, but you're better off leaving those alone until you can recognize what is bad seeing versus bad collimation. With bad collimation, you'll often see one side of an object always fuzzier than the other. Stars may look asymmetric, like little bumblebees. On nights of excellent seeing you will still have a "soft" view that you can't quite focus. But don't assume it's bad collimation until you've ruled out bad seeing, poorly made optics, or even the nature of the type of optics. 

For example, a "fast" reflector with a small focal ratio, for example f/5, will normally show "coma" at the outer edges of the field, an abberation that makes stars near the edge look like comets. Same with achromat refractors and "chromatic abberation," where you may see blue or yellow color fringing along the edges of bright objects at higher powers, an indication that the focus is going to be a bit soft. These abberations are inherent in the design. Because most everything in life is a compromise.

Learning the sky

Using a telescope is like driving a car. You can learn to drive it, but if you don't know where to go or how to get there it won't do you much good. Even if you have a go-to telescope, the equivalent of an autonomous-driving car, knowing what you want to see, when is a good time to see it, and knowing what to look for are important for enjoying your observing.

Many experienced amateurs recommend buying a book to start learning. That's fine if you are a book-learner, but with so much information available on the internet, with options to ask questions and interact with other people, I wonder if starter books aren't a little obsolete. With younger people especially, I don't think learning from a book is a very appealing process. I think it just depends on the individual.

I did start with some books, but most of my actual learning came from simply getting out and observing, and then reading about the objects I saw. Back then, the charts in the book were most important for me, but with charting apps that's changed. Unlike paper charts, apps are flexible, can be zoomed in and out and filtered and manipulated however you want. So many nights I wished my paper charts went deeper than what they showed. And don't get me started on trying to find the right chart late at night for the area I wanted to observe!

Start with things that are easy to find: the Moon, the bright planets, M42, the Orion Nebula (winter), or M8, the Lagoon Nebula (summer), and brighter star clusters. 

We measure the brightness of celestial objects primarily by "magnitude," with higher numbers meaning dimmer, and lower numbers, including negative numbers, meaning brighter. The magnitude scale is reverse logarithmic, therefore a difference of five magnitudes is 100 times brighter or dimmer and each difference of 1 magnitude is about 2.5 times brigher or dimmer. 

Venus varies from magnitude -3 to almost -5. The bright star Vega is a reference at magnitude 0.0. The limiting magnitude of the unaided eye (dimmest you can see) in a transparent, dark sky is around magnitude 6 or 7. A typical 3-inch (80mm) telescope can reveal stars to about magnitude 12. A 6-inch (150mm) to about 13.5 magnitude. An 8-inch (200mm) to about magnitude 14. This doesn't sound like much of a difference, but it makes a big difference in what you can see when so many stars and deep sky objects are at these threshold levels for seeing details, or just seeing them at all.

Extended objects like larger nebulas and some more diffuse galaxies will appear dimmer than their listed magnitudes might indicate, in which case we say they have "low surface brightness." This is one of the reasons a larger aperture that collects more light can show many deep sky objects better than smaller ones. 

Once you are familiar with using the telescope and have seen some of the brightest objects, observing the rest of the Messier Objects is a good next step. Some of them are more challenging than those in the much larger NGC catalog, but the rest are some of the biggest and brightest. Be realistic in what you try to observe, but once you gain experience, don't be afraid to try for something normally just out of reach if you have a great sky. That's part of the fun of observing!

Navigating the sky

Learn how to navigate with your telescope, depending on what assistive equipment it has. Regardless, learn how to starhop. This means comparing the patterns of the stars you see in your finder or eyepiece with those on a chart and moving the scope to the object you want to see. Unless your go-to or push-to system is really precise and functions flawlessly every time (ha!), you will still need to recognize star patterns and be able to hop to the object from where your navigation system takes you. Knowing how to starhop will also ensure you can continue observing even if your electronic system fails or runs out of power—not an uncommon occurrence.

Observing

Don't expect deep sky objects to look anything like the images you see online or in books. Your eyes, even with the help of a telescope, can't gather as much light or see most of the wavelengths represented in images. So most objects will be white or gray and look rather like dim fuzzy blobs or patches, if you can glimpse them at all. Star clusters on the other hand, at least the ones your telescope can resolve into individual stars, will look like sprinklings of beautiful points. 

Once you learn how to observe and spend 10 minutes or more viewing an object, very subtle detail will eventually start to reveal itself on clear and steady nights. Learn to appreciate what you are looking as much as how it looks.

Except when viewing the Moon or bright planets, let your eyes get accustomed to the dark, which takes about 20-30 minutes for full dark adaptation. Use a dim red light when you need light.

As you observe more, you will learn what different objects look like, what to expect, what to look for, and how to improve your observing skills. Astronomerica has articles on using averted vision, understanding distances and directions in the sky, observing the Moon, observing the brighter planets, and observing galaxies, to name a few. The internet has a huge amount of resources.

Modifying and tweaking

Even a high end telescope may require some modification and tweaking by the user, if only to customize it to your own satisfaction. Inexpensive telescopes will almost always require some modifications to get the most out of the equipment, so expect that and don't be afraid to experiment. 

Right: I added the right angle bracket and 6x30 finder to my 6-inch tabletop telescope. I also added the light-blocking craft foam, a hose clamp and extra long focuser thumbscrews to improve the helical focuser. These are all reversible mods.

However, don't start making changes until 1) you're sure you are going to keep the telescope, to avoid return or warranty issues, and 2) you've tried it as is and determined there is a modification that you can do yourself that will likely make it better. Mods for specific telescopes are abundantly available online, often offering multiple options to solve common problems. The safest mods are those that can be undone to return the scope to its original condition.

Don't rush to upgrade

Once you're comfortable with all of the above, then you can think about upgrading. Or not. You really don't need a lot of gear to see a lot. You mostly need clear dark skies, good seeing, time, patience, enthusiasm, and experience. You can't buy that. 

Unless you are missing a critical piece of gear or it just doesn't work, upgrading equipment should be the last thing on your list. You might find yourself buying a lot of stuff you don't need, won't use, or will have to rebuy once you determine what items you really want or need after observing for a while.

The important thing is to get out under the stars.

Equipment Tip: Use adhesive craft felt on cold surfaces

Most telescopes are made of metal. Metal gets very cold in the winter and touching it, even with gloves on, sends a chill through your body. Even on relatively warmer nights, metal will still get uncomfortably cold to the touch. This tip is mostly applicable to Dobsonians that require you to grab the tube to position it, but may also apply to other scopes and gear.

Putting patches of adhesive craft felt on touch points can really help keep your fingers from freezing.

Next time you are out observing, take mental notes of where you typically touch the telescope. If these points are metal and relatively smooth, you can cut pieces of adhesive felt to fit. 

On my 10 inch Dobsonian, I have craft felt along the lip of the aperture and on the lower half of the tube where I rest my hands when moving the tube (arrows in image at left). For shorter tubes, I'll place the felt along part of the edge of the mirror holder at the back. It really does make a difference.

Cheap telescopes: What to expect, what to look for

I spend time on several online astronomy forums and see this question all the time:

"What telescope should I get? I have $100 to spend."

Left: Too many super cheap telescopes end up in the thrift store. Sadly, they knew they would.

Constructive responses from amateur astronomers usually include one or more of the following:

• Clarifying questions: what do you want to see, what is your interest, how dark or light-polluted is your sky, etc.
• Save your money until you can spend more
• Find a used telescope
• Check out your local astronomy club
• Buy binoculars instead

All of these responses are quite valid and contain good advice. There is endless data online about recommended telescopes and equipment, which I won't delve into here. 

Most "experts" will tell you these cheap telescopes are all junk and are "hobby killers." However, I have seen many comments by avid amateurs who started with just such a telescope and the thrill of seeing craters on the Moon or Saturn's rings for the first time set them on a lifelong path as an amateur astronomer. I think a far more reliable determinant of whether someone will catch the astronomy bug is the person rather than the equipment. I think that's the case for most everything related to astronomy—or anything else, really. Nevertheless, if you can afford spending a bit more, you will likely get a better telescope and enjoyment for a longer period of time and without as much frustration.

You will see some reviews of ultra cheap telescopes saying how fantastic and awesome they are, primarily because most of the reviewers never looked through a telescope before and ANY view of the Moon's craters, for example, will elicit that type of response. If that's all you're after, then maybe dipping your toe in the cosmos like this is enough. But after that initial "wow" moment, the cons start stacking up. I think this quote from a $100 telescope five-star review on Amazon says it all:

"...if I could do it over again, I would've spent more and gone with a better one."

However, for various reasons, all of the above advice may not be feasible or practical for you. For example, maybe you just don't have $300 to spend on a telescope. While you are slowly saving money, the prices are slowly going up. You're not sure if your kid is going to use it and you don't want to spend hundreds of dollars finding out. You may not be comfortable looking for a used telescope, not knowing what's good and what isn't. You may not have a local astronomy club, or can't get to one. With binoculars, you're not going to see much detail on the Moon and none on the brighter planets—it's just not the same as the telescope experience.

If you don't follow the above advice, here's what you can expect, and here's what to look for. The key criterion is enjoyment, and that depends on the individual and your expectations.

What to expect from a cheap telescope

Most telescopes recommended by amateurs start at about $300 these days, although sometimes you can get one on sale for cheaper, especially in the used market. So we're talking about sub-$300 (new) telescopes. This is the total price for the optical tube assembly (OTA, the telescope itself), a mount that moves in two axes, and a tripod or base on which the tube and mount are placed. You also need at least one eyepiece (the lens that you look through), some type of lower power finderscope attached and aligned to the main telescope so you can find things in the sky, and some type of chart or software that tells you where those things are. Some telescopes come with all of these pieces, especially the ultra-low end scopes. That doesn't mean they all work well, or at all.

With a cheap telescope, you can expect the following:

• Shaky views. Manufacturers usually skimp on the mount and tripod. Your view in the eyepiece, especially the higher the power you use, will vibrate uncontrollably any time you touch any part of the telescope. So if you are trying to focus, you will have to move the focuser a little, wait several seconds for the view to steady, decide if it's better or worse, and repeat until you get it in focus. All the while, the object will appear to move out of the field of view because the Earth (with your telescope attached to it) is turning and the sky is not. When you move the telescope to get the object back in view, you will again have to wait for the scope to settle. This can be frustrating, but not necessarily terminal.
  
  
  
  
  
• Blurry views. Most cheap telescopes either have poor main optics (the refractor lens or reflector mirror), or poor eyepieces (the lens you look through), or poor mirror diagonals (for refractors, to bend the light 90 degrees so that you can look high in the sky at a reasonably comfortable angle), or all three. Some main optics are better than others, but the view will still not be as sharp as that of a higher quality telescope. Finer lunar detail available to a scope of that size may not be visible, the edges of the bright planets may not be well-defined, moon shadow transits of Jupiter are often difficult to make out, color fringes appear on the edges of bright objects, and stars may be misshapen blobs rather than pinpoints.
  
  IMPORTANT NOTE: These same effects may be the result of poor atmospheric "seeing." This is the case in the eastern U.S., for example, which is under or near the jet stream and is often subject to poor seeing. The view will appear be ripply as if viewing a stone in a shallow stream, or soft and blurry. If possible, observe objects when they are higher in the sky, where you are looking through less atmosphere. Also avoid viewing directly over pavement, rooftops, cars, or other objects that radiate heat at night. If the seeing is bad, switch to a lower power eyepiece where the effects are less noticeable. Or wait for a better night.
  
  
• Jerky movements. Going back to the mount and tripod or base, the movements of the axes (left and right, up and down) are usually not very smooth, so it becomes difficult to place an object in the center of the field of view, and then recenter it each time it drifts out of the field, sometimes overshooting it and then losing it completely.
  
  
• Difficulty finding objects. This is usually the most frustrating aspect and one which causes a lot of cheap telescopes to end up in the closet or the dumpster. The other defects above may still allow you to enjoy using the telescope if you have patience and reasonable expectations, but this one is terminal if not addressed. Most cheap telescopes come with very cheap finderscopes or red dot finders, and sometimes the design does not even allow you to easily replace them later on down the road. Also, if you don't know the sky, you will be limited to the Moon and maybe Jupiter and Saturn. You WILL need to learn the sky.

• No imaging capability. These cheap telescopes are not designed for imaging, which requires a tracking mount and a much more robust build. With some practice, you can hold your phone up to the eyepiece and snap a fuzzy view of the Moon. That's about it.
  
  

With these defects, or should I say challenges, in mind, you can usually work around most of them to be able to see craters on the Moon, the four brightest moons of Jupiter, the rings of Saturn, maybe some slight detail on these brighter planets, and brighter double stars. If you are in a dark enough sky, you can glimpse some of the brighter deep sky objects, such as star clusters and a few galaxies and nebulas. 

So if you don't take the advice above and still end up buying a cheap telescope, with some patience and resolve, you might still get some enjoyment out of it. Just don't expect anything close to the images you see online. Not even close. Even big expensive telescopes can't compete visually with images from even mediocre telescopes.

Except for some stars that show subtle color, a yellowish or chalky gray color to the Moon, and some muted colors in the bright planets, almost everything else will be shades of white or gray. These objects can still be fascinating and quite beautiful, but you have to appreciate what you are seeing, not just what it looks like in the telescope. It's a thrill to see these incredibly huge and distant objects through your own telescope with your own eyes! If it isn't, then maybe a telescope isn't the right thing for you or your child. No problem, we're all different.

Cheap telescope as a toy

Do not give a child younger than about 8 years old a telescope. It's just not something most of them have the patience or understanding to operate and appreciate. Expect that you, the adult, will be the one having to learn the sky and find objects for young children. A cheap telescope will stretch your own limits of patience.

A telescope given as a toy is just that—a toy, and won't function as a precision instrument. Telescopes make bad toys. A $30 pair of binoculars would make a better gift once the child is old enough to know not to look at the Sun, and is also a functioning instrument that's a lot easier to use, for a lot less money. 

What to look for

• The most critical part is the mount and tripod. Thicker, adjustable legs on the tripod, a heavier mount, and a spreader to keep the tripod legs from collapsing are all good. Most cheap telescope tripods are not tall enough to allow an adult to observe without bending over. But that's okay, because sitting is more comfortable and allows for a steadier view at the eyepiece. Look for 1/4-20 mounting threads on the telescope tube assembly so that you can upgrade to a better photo tripod. Many of these, whether new, used, or from a thrift store, will be better than what comes with the telescope. 
  
  Above: Many cheap scopes come on wobbly pan-tilt photo-style tripods such as this one, but if the thread on the top is the standard 1/4-20, you can upgrade it to a heavier photo tripod at a later date.
  
  
• Ignore claims of what power a telescope can give you ("High powered telescope!!"). The power, or magnification, is determined by the combination of the focal length of the telescope and the focal length of the eyepiece. Most cheap telescopes, and some good telescopes, will not give you any kind of clear, bright view over about 100x, often much less (x is the power). That is still enough to see many objects within range of the telescope fairly well. In fact, some large objects are better in lower power.
  
  
• Assuming equal quality, the most important optical characteristic to consider is the size of the aperture. The larger the aperture, the more light the telescope collects, making typically very faint celestial objects a little brighter and detail a little easier to see, even on brighter objects like the Moon and Jupiter.
  
  
• For cheap reflectors, parabolic mirrors are generally better than spherical mirrors. That doesn't mean a spherical mirror can't produce a decent image, at least in the middle of the field of view, but it is a cost-saving measure, not a feature, and it's best to avoid it.
  
  
• Eyepieces and barlow lenses that, combined, give no more than 150x, and often even that is way too high. For example, many telescopes come with 25mm and 10mm eyepieces. For a scope with a 700mm focal length, those eyepieces will give you 700/25=28x and 700/10=70x, which may be reasonable. If you put the eyepiece into the included 3x barlow (tripling the magnification at the loss of a lot of sharpness and brightness), you would have 84x (still possibly okay) and 210x (too high for pretty much all of these telescopes). What happens with too much magnification? It dims the view down, it becomes very blurry, it magnifies the scope's jitters, and it becomes even more difficult to track an object as it speeds through the tiny field of view.
  
  In my opinion, the maximum usable power for a cheap telescope with a cheap eyepiece is about equivalent to the aperture in mm. This is under perfect conditions (very steady atmosphere), which may not happen very often depending on where you observe. So for a 70mm telescope, 70x; a 90mm telescope 90x. This is about half of the generally recommended 50-60x per inch (25mm) of aperture for higher quality telescopes. Under perfect conditions. Divide the number in half and you're probably closer to typical effective use.
  
  
  
  
  
• A red-dot finder. In most cases, a magnifying finderscope that looks like a mini-telescope attached to the main telescope will be too small and dim to see anything well through it. A red-dot finder, however, allows you to point the dot at what you want to view and, if aligned properly, you can then view it in the main telescope. It's very intuitive. If the telescope comes with a magnifying finderscope, it will likely be a 5x24, which is frustrating to use and you won't see many stars at all in it. A 6x30 is better. A red-dot is probably best for a beginner.
  
  
• Generally for small refractors and reflectors, a shorter tube (shorter focal length of around 300-800mm) for a refractor or reflector means lower power, wider views, better for dark skies and viewing larger star clusters and galaxies. A longer tube (longer focal length of around 800mm or more) will generally give a more magnified view using the same eyepiece, but with a narrower field, better for the Moon, bright planets, double stars, and smaller objects.
  
  Note: If you see a short tube reflector and it has a long focal length listed, this may be a Bird-Jones design, with a spherical mirror and corrector lens, which is almost always poorly rendered in cheap telescopes. The infamous Celestron Powerseeker 127mm reflector is a good example.
  
  
• Many cheap telescopes now come with cell phone adapters, remote shutter buttons, cheap barlow lenses, and moon filters. Ignore these mostly useless accessories when you first start out. You can probably take cell phone photos of the Moon through the eyepiece easier without the cell phone adapter. Barlows that come with these scopes are generally too cheap to be satisfying long term and give dim, blurry views, but may be exciting at first. If the scope comes with one or two, try them out and decide for yourself, but get the object in view in a low power eyepiece first, remove it, insert the barlow, then insert the eyepiece into the barlow.
  
  
• For a refractor, make sure it has a 90 degree diagonal. Many only come with a 45 degree diagonal, which is fine for terrestrial use, but unsuitable for observing high up in the sky, where the sky is usually darker and steadier. The 90 degree diagonal lets you place your head and eye at a more comfortable position, which is key for observing.
  
  
• If shopping used, avoid older telescopes with .965" focusers and eyepieces. The standard today is 1.25" and many better scopes come with 2" focusers with 1.25" adapters. There may still be a few cheap new telescopes using the .965" size. These are narrower eyepieces, and options to replace cheap ones with better ones are very limited. You can sometimes use a 1.25" eyepiece with an adapter in a .965" focuser, but it won't work well, if at all, in many telescopes. Go with 1.25".

If you must buy a cheap telescope, I recommend first reading the telescope rankings on Telescopicwatch.com, which start with the cheapest at the top.

Let's look at a sample listing

Here's the Celestron Travel Scope 70, a 70mm (diameter of the main lens) refractor with a basic tilt/pan camera type mount on a tripod, with a 400mm focal length. It has a list price of $119.99, but it was on sale on Amazon for "Prime Big Deal" days in October 2025 for $99.99 and around $75 on Black Friday 2025. 

I have not used this particular telescope, so I am going only by the specs and the reviews of other users. I can therefore not say whether I personally would recommend this telescope or not versus others in its price range. This is just to illustrate how you would go about assessing the telescope for your own needs from an online listing. If you are interested in a particular telescope, read the reviews and ask others who have it on astronomy forums such as cloudynights.com or Reddit r/telescopes. See the review of this scope on Telescopicwatch.com.

The specs:

It's a 70mm refractor, with a 400mm focal length, making it a focal ratio of f/5.7. Let's break that down:

70mm - This is the aperture, which determines how much light the telescope collects. The more the better. 70mm (2.8") is relatively small, so only brighter objects will show up and the resolution, or the fineness of detail, that you can see through it will be relatively low. Hint: getting any telescope to a dark sky will let you see much more!

400mm - This is the focal length of the telescope. Divide by the aperture to get the focal ratio (400/70=5.7).

f/5.7 - An f/5.7 telescope is on the "fast side," providing lower power views and wider fields, but still "slow" enough to forgive some optical defects in the eyepieces.

The good (maybe):

• Celestron designs, manufactures, and sells astronomical telescopes and gear. In fact, they are one of the most well known companies selling astronomical gear. That doesn't mean all their telescopes are good, but they know when they are selling crap. The low price provides a clue on this one, but some crap is better than others.
• Appears to have a 1/4-20 attachment point, allowing you to upgrade to a better photo tripod.
• 90 degree diagonal, suitable for astronomy, although it will mirror-reverse your view, which is normal. It also comes with a 45 degree correct image diagonal if you want to view nature or other terrestrial scenes.
• No cheap barlow. You can buy a better one anyway for less than $20 if you need it. The backpack is more useful.
• Decent eyepiece focal lengths, giving 20x and 40x. This is very low power for an astronomical telescope, but okay for a scope of these specs. The Moon will easily fit in the field of view and Jupiter and Saturn will be quite small, with surface detail very difficult or impossible to discern. Saturn's rings will be visible when tilted at an angle (right now they are almost on edge). Jupiter's moons will be visible. Larger, brighter deep sky objects like the Pleiades and M31, the Andromeda Galaxy, and M42, the Orion Nebula, will be framed fairly well. Smaller objects will be very dim and tough or impossible to see unless you are in a nice dark sky. Hint: for deep sky, start out looking at open star clusters, which will show up better. Skip most of the galaxies and nebulas until you have more experience and can observe in a dark sky.
• Lightweight and portable for camping, hiking, etc.

The okay.

• Small 70mm aperture and short focal length limit you to low power, wide field views and low resolution.
• Backpack is useful if you want to hike to a darker, more open site and protect the scope during transport. 
• Starry Night software for the computer is fine, but there are other good cheap or free options,  including mobile versions (Sky Safari, Stellarium) for easier use at the telescope.

The bad.

• Tripod is rickety, although it has a spreader, and is adjustable for sitting height only. Views will be jittery and bounce around a lot.
• Altitude/azimuth mount like a cheap camera tripod (tilt/pan). Not easy to position objects and tends to be jerky when trying to move the view around.
• 5x24 finderscope is small and dim. It will be difficult to find objects by looking at a chart and "starhopping" to the right location.
• No idea about the quality of the eyepieces. Likely low quality but usable.

Upgrading

Sometimes it's worth upgrading certain parts of the telescope, usually the eyepieces, diagonal, finder, and/or tripod/mount. This may be a good strategy if you like the scope but find some parts are annoying. It can help you spread the cost over time and still be enjoying the scope from the get-go.

Here are some cost estimates for minor upgrades, i.e., parts that are a bit better but not overkill for a cheap telescope:

• Eyepiece: Different focal lengths allow you to achieve different powers. Don't go overboard with high power. Views get dimmer and blurrier beyond a certain point. (Recommended price range: around $35 per eyepiece. Often recommended: Svbony "redline" series)
  
  
• Finder: Red-dot finders do not magnify and are more intuitive. Just point the dot where you want to look (after making sure it is aligned to the view in the eyepiece). Make sure the finder bracket will fit the mounting bracket on your telescope! (Recommended price range: $15-30)
  
  
• Barlow lens: A barlow lens adds magnification. You put your eyepiece into the barlow, then insert the barlow in the telescope focuser. 2x, or at most 3x, will give you higher magnifications. Again, don't go crazy with high power. (Recommended price range: $15-25. I have the Svbony SV137 2x barlow and find it to be a great value for the price.)
  
  
• Tripod: Sometimes the optical tube assembly is pretty decent, but the mount and tripod are almost always too unstable on these cheap telescopes, which leads to frustration. Your best bet is to look in a thrift store for a working photo tripod. You can get them online, too, but it's harder to tell how sturdy it is. Just make sure it's an improvement over your current one and that your telescope or mount has a 1/4-20 thread so you can mount it on a standard photo tripod. (Recommended price range for new: $30-50, but only if it's sturdier than what came with the scope and it fits.)

If you upgrade all of the above parts, you'll end up spending at least $95. Consider that you might just want to buy a better telescope from the start, if that's possible.

Bottom line: Take the advice at the top of this post. If you just can't, then approach a cheap telescope with very low expectations and a large amount of patience, learn the sky, and get as much enjoyment out of it as you can. But don't say I didn't warn you!

SAFETY NOTE: Never point a telescope at the Sun, even when no one is looking into it, without a full aperture reputable solar filter designed for visual observation securely fastened over the aperture and the finderscope capped. Supervise children and don't leave the scope unattended when the Sun is up. For terrestrial viewing with small kids around, it's best to set it up in the shade. If your telescope comes with a little solar filter that screws onto an eyepiece, smash it with a hammer and throw it away, it is dangerous to use!

Astroboy cartoons by Astronomerica.

Equipment Tip: Stop your dovetail clamp from marring your dovetail

There's a joke somewhere in the title of this tip, I just know it. Not sure what it is, though. Anyway, here's one for those who have a dovetail clamp on their mount that has a rounded screw tip or tips that hold the scope to the dovetail. 

The problem is, the screw is steel and the dovetail is aluminum, so it leaves dimple marks in the dovetail. If this doesn't bother you, problem solved. But for others, it's a little irksome. It's kind of like focusers with thumbscrews that mark up your eyepiece barrel. It doesn't affect the function at all, but we'd rather keep the eyepiece clear of marks.

Some people just buy a new dovetail clamp that has a flat contact surface, such as the Svbony medium dovetail clamp shown at left. But something like that will cost you around $25-40, and Astronomerica is not about wasteful spending.

Instead, get a 1/2" x 1/16" thick flat bar of aluminum, cut it to length easily with a hacksaw, file and sand the edges smooth (be careful, they will be sharp!), and use double-sided tape to stick it to your dovetail. Problem solved and you didn't have to buy a new dovetail clamp. Now the clamp only mars the aluminum piece.

I found just such a piece of aluminum for a few bucks at my local home improvement store. It's three feet long, so enough to protect the dovetails of even a very large family of amateur astronomers!

Downsizing again: The Sky-Watcher 102mm Mak

I'm not one who tends to buy a lot of telescopes. I started in 1991 with a 4.5 inch Tasco 11TR reflector on a German equatorial mount and a tripod. I used that regularly for 13 years, so if you think you'll outgrow a small telescope quickly, think again.

Then I decided to go for a Dobsonian because the 4.5 inch's tripod had literally fallen apart from use. I built a Dobsonian mount for the tube and it worked great. But I wanted more aperture, so I went as big as I could comfortably go, physically and financially, and got a 10 inch GSO Dob. I used that regularly for 20 years. 

Nine months ago, as a result of declining health, I could no longer manage the 10 inch. I separated the base into two parts that could be easily reassembled with four knobs, and I devised a simple rope harness to go around my shoulders to help carry the tube, but that wasn't enough. Very reluctantly I realized it was time to start downsizing. 

I chose the Sky-Watcher Virtuoso GTi 150P 150mm (6 inch) f/5 tabletop scope with a go-to/tracking base. I figured the tracking might help soften the blow of the loss of 4 inches of aperture. It helped a little, and I've gotten used to it, but the views in the 10 inch are just so much better. You do what you have to do.

As my health continues to decline, I can sometimes no longer even set up the 6 inch comfortably, so I decided I would need to downsize again, this time to a true "grab and go" telescope. My requirements were:

• 15 lbs. max total weight
• Carryable out the door in one piece (it's okay to come back for the observing stool)
• Good on the Moon, bright planets, and double stars because I would be using this from my light polluted home, reserving the 6 inch for any dark sky forays
• No cool down required

I settled on a Sky-Watcher Skymax 102mm (4 inch) Maksutov-Cassegrain. This scope, made by Synta, is an F/12.7, with a 1300mm focal length. The optical tube assembly (OTA) weighs less than five pounds.

This means my Svbony SV135 6-element 7-21mm zoom is all I need, giving me 62-186x in a single eyepiece, with exit pupils (aperture in mm / magnification or eyepiece focal length in mm / telescope focal ratio) of 1.6 to 0.5, good for seeing detail in bright objects.

Now I have the smallest telescope I've ever had (not counting the little Svbony dedicated solar scope), but...and this is the key...I can use it! 

I mounted it on the Svbony SV225 alt-az mount that I used on my trip to Arizona in 2024. I had bought this as an alternative to the go-to/tracking mount that came with the 150P. I can mount the 102 on the Virtuoso mount if I want tracking. In fact, Sky-Watcher sells a Virtuoso package with a 127mm Mak.

I don't really like tripods, but decided a tripod was the way to go with this setup for several reasons:

• With a tripod, I can lift the telescope and bring it in and out of the house without bending over or crouching down. Those of you with bad backs, bad knees, or similar issues will relate. This makes a big difference.
• The tripod is adjustable to match the height of the very lightweight GCI PackSeat observing stool I've been using with the tabletop scope. I can easily pick up that stool with one hand under the seat. It weighs about a pound. My homemade adjustable observing chair weighs around 15 lbs.
• I can mount other small telescopes on it as long as they have a standard Vixen style dovetail to fit the SV225 dovetail clamp. That includes my 150P.

I chose the Sky-Watcher Star Adventurer tripod. It's pretty sturdy for being inexpensive and I like that it has a tray for my eyeglasses, since this is my "quick look" scope and I don't want to have to put my contact lenses in for very short sessions. To fold up the legs to get through the door and around objects more easily, I can easily take off the tray with a simple twist, then put it on again outside.

I took the Svbony SV182 6x30 right angle correct image (RACI) finderscope off my 4.5 inch and put it on the Mak in place of the red dot finder that came with it (image at left). I can't do the contortions necessary to use straight through finders anymore. I wasn't using the 4.5 inch much anyway. It uses .965 eyepieces, and although I have some decent ones from Orion, they just aren't as nice as my 1.25" eyepieces.

A 6x30 finderscope is not ideal for a light polluted sky, but good enough for quickly finding the Moon or bright planets and stars. There just aren't that many stars bright enough to be visible in a 30mm finder in bad light pollution.

The 102 is designed to be mounted on top of a mount, not side-mounted, as I would have to do with the SV225 mount. I wasn't sure it would work, but it does. I just rotate the diagonal off to the left side a little and I can use both the main eyepiece and the finder well at any altitude setting. I had to partially take apart the mount to free up the setting circles so I could adjust them as needed, but now I can find anything using them and the finderscope.

The whole setup weighs about 15 lbs. I can move it easily in and out of the house for quick looks at Jupiter, Saturn, the Moon, or maybe some double stars or brighter deep sky objects. That's all I can see from my light polluted neighborhood anyway. It is truly "grab and go."

Avoiding cool down thermals

My fourth requirement was that no cool down be required, because I wanted to be able to pop outside with it to take advantage of a break in the clouds or just a quick look. But it's a Mak, which needs cool down, right? How can that work?

A few years ago, Cassegrain users started wrapping their telescope tubes in an insulating material, usually Reflectix, which is basically bubble wrap with a reflective layer on both sides. This prevents the scope from cooling unevenly and developing internal heat plumes as a result, which ruin seeing.

The wrap will slow this cooling down and keep the remaining heat distributed more evenly thoroughout the interior of the tube as it slowly cools. This allows observing immediately without waiting for the scope to cool down. It won't fix bad seeing (rats!), but it will make sure the scope is not to blame.

I got a 16" x 5' roll of Reflectix and found that 16" is a great length for the wrap on this scope. This includes about five inches of overlap in front for an integrated dew and glare shield, with adhesive-backed black craft felt such as this lining the inside to avoid reflections. Attached to itself with adhesive-backed Velcro, the "jacket" can be removed easily. Some say it looks ugly, but I say it makes it look like I'm observing with the Hubble Space Telescope!

I've had it out a lot already, and although it appears to be very slightly out of collimation, it's not enough for me to start fiddling with it. On nights of decent seeing (about the best we get here), I can see the five brightest moons of Saturn and detail on the planet. Stars in high power are nice and sharp with crisp Airy disks. 

For example, Alpha Piscium (4.1 and 5.2 mag at 1.8" separation) splits cleanly in 7/10 seeing, although component B is right on the first diffraction ring. That's about the practical resolution limit of the scope. I'm happy. 

Above: Simulated view of Alpha Piscium in the 102mm scope at about 170x.

Note: I noticed in writing this that a lot of what I have bought lately is either branded Svbony (products manufactured in Mainland China) or Sky-Watcher (a distribution company for Synta products of Taiwan). While I'm not beholden to either of them (I buy my own stuff with my own money and don't have any brand loyalty), they seem to be among those offering some of the better quality inexpensive astronomy products lately, with the caveat that most inexpensive gear requires some tweaking or modifying to work to its fullest potential.

(Human evolution silhouettes by M. Garde after José-Manuel Benitos, Wikimedia, CC By-SA 3.0, modified with telescopes by Astronomerica)